Alcohols have a variety of industrial and scientific applications such as fuels, reagents, and solvents. For example, butanol is an important industrial chemical with a variety of applications including use as a fuel additive, as a feedstock chemical in the plastics industry, and as a food-grade extractant in the food and flavor industry. Accordingly, there is a high demand for alcohols such as butanol as well as for efficient and environmentally-friendly production methods including, for example, fermentation processes and the use of biomass as feedstock for these processes.
Production of alcohols by fermentation is one such environmentally friendly production method. As such, effective production of a stable, transportable yeast product for large-scale, commercial fermentations is desirable. Accordingly, there is a need for production methods and genetic modifications which provide attributes advantageous for commercial use.